Head Substrate Isolation Layout for Accurate Heater Temperature Sensing

The patent segments the electrical circuit into isolated units by providing separate well layers (first well layer and second well layer) for different circuit components. This segmentation prevents electrical noise from the high-power electrothermal conversion element circuit from coupling into the temperature detection circuit, allowing both high power operation and accurate temperature detection to coexist.

The patent introduces an intermediary structure (deep element isolation portion extending into the substrate) between the first well layer and second well layer to provide electrical isolation. This intermediary prevents direct electrical coupling between the noisy power circuit and the sensitive detection circuit, thereby reducing noise interference while maintaining functional separation.

The patent merges multiple isolation functions into a single integrated structure. The deep element isolation portion simultaneously provides electrical isolation between well layers, mechanical support, and stress management, reducing the need for additional separate isolation components and minimizing overall device complexity despite the enhanced isolation capability.

The patent transitions from planar isolation to three-dimensional isolation by extending the element isolation portion vertically into the substrate. This dimensional change provides effective electrical isolation between well layers without requiring increased lateral space, thereby maintaining compact device geometry while achieving superior noise reduction.